The present invention relates to an apparatus for automatically forming a plurality of packages of groups of articles. More specifically, the present invention relates to a robotic containerization system (RCS) that is configured for the efficient loading of U.S. Postal Service (USPS) mail containers such as all purpose containers (APCs) and pallets.
In a typical USPS operational facility, trays of mail are generated at various sorting operations. These trays are used to transport the mail between sorting operations, and once they have reached the level of sorting necessary for dispatch, they are placed on a conveyor that takes them to the dock area for transport to other facilities. On the dock, the trays are sorted to the destination facility, and loaded into containers. Depending on the destination the trays may be sleeved and strapped (for the air transport or long truck transport), or may be left opened for local truck transport. In most conventional facilities, the sorting and container loading process is performed manually.
There are several problems inherent in systems of the prior art for performing these sorting and loading operations. In the early portion of transit of an article passing through the system, the rate of generation of trays will be low, such that even one person located at a given run-out conveyor will be under utilized to keep pace with the rate of arriving trays. However, during heavier volume, the mail handler is faced with a demanding labor-intensive task involving repetitive heavy lifting (up to 35 pounds for trays, 70 pounds for flat tubs). Due to the demanding nature of the tasks and the varying conditions of the trays, the risk exists of dropping a tray, further reducing the efficiency of this operation. In an attempt to reduce labor costs, reduce work place injuries and improve operational efficiency, the USPS has typically deployed robotic work cells to perform the container loading functions. Currently, the USPS is deploying pedestal robot work cells that perform a 12-way sort and container loading function, and gantry robots. These cells utilize conventional material handling robots that are typically manufactured for extremely heavy-duty, high precision applications.
The gantry robot layout is more floor space efficient than the pedestal configuration, but the gantry robot requires significant head-room (approximately 13 feet) or a very specialized telescoping Z axes. Gantry robots tend to be large and expensive also. Although the gantry can be configured to meet specific operational needs of a facility once installed, it cannot easily be modified if operational requirements change.
The operation of these robotic cells has very similar characteristics. Trays arrive on an input conveyor in a random sequence. A bar-code reader at the end of the conveyor scans the tray and determines the appropriate container. The robots utilize a vacuum gripper that picks up one tray at a time. The use of a vacuum gripper requires that the tray be sleeved and strapped so there is a flat surface on top of the tray for the suction cups to grab. These grippers of the robots transporting one tray at a time result in system throughputs of approximately, only 6 to 7 trays per minute.
Accordingly, a need in the art exists for an improved automatic container loading system configured for more efficient loading of USPS mail trays into USPS containers such as all purpose containers (APCs) and pallets.